DESCRIPTION: (Applicant's Abstract) The candidate, Wendy Walwyn, Ph.D., is a post-doctoral trainee in the NIDA-funded Opioid Research Center (Director Chris Evans, Ph.D.) and is currently supported by a NIDA Training Grant (P.I. Doug Anglin, Ph.D.). The proposed research plan is multi-faceted involving techniques ranging from molecular biology to behavior. The wide scope of the project is made possible by the diverse expertise of the faculty within the Opioid Research Center. The candidate will therefore receive training in molecular biology (Boulter lab), cellular biology (Evans lab), electrophysiology (Xie lab) and behavior (Maidment lab). In addition, virology support will be provided by the Feldman lab. Such diversity of training will prepare the candidate for her long-term career goal of becoming an independent investigator in synaptic plasticity as it relates to substance dependence. The research goal is to use viral-mediated gene transfer techniques to study the role of opioid receptor desensitization and internalization in the development of opiate tolerance in vivo. Mutated mu opioid receptors with previously demonstrated deficiencies in their ability to be phosphorylated and/or internalized when expressed in cell-lines will be expressed in pain processing neurons of mu opioid receptor knockout mice. Such neurons will be examined both in culture and in vivo for their response to opioid agonists using measures of phosphorylation, internalization, receptor-effector coupling and, ultimately, whole animal behavioral analysis of analgesia.